1. Background Field
The present invention relates generally to localization of objects and more particular, to ranging of multiple objects using channel estimation.
2. Relevant Background
Location Based Services (LBS) often use satellite based positioning systems, such as the well-known Global Positioning System. For indoor locations, however, satellite based positioning systems, are problematic due to poor signal reception as well as relatively poor resolution. For example, when a satellite based positioning system is used for localization in an indoor environment, the resolution of a few meters that may be achieved with satellite based positioning systems may result in an object being located in an incorrect room.
Typically, when tracking objects or persons in indoor environments, resolution that is superior to that achieved by satellite based positioning systems is desirable. Ranging to access points in the Gigahertz bandwidth range may be used to achieve desired resolutions in indoor environments. Ranging to access points, however, may require the temporary suspension of transmission from access points, such as WiFi™ Thus, it may be desirable to search for multiple objects simultaneously when ranging to access points to reduce amount of time of the suspension of transmission from the access points. Accordingly, it is desirable if multiple objects can communicate with the access points simultaneously. Unfortunately, interference between signals broadcasted by objects being tracked may be problematic with respect to channel estimation, which is necessary to identify which signals are associated with which object.